In the human body, articulating joints are surfaced with hyaline cartilage, which is a durable natural material with a low coefficient-of-friction. Such hyaline cartilage surfaces can become damaged over time when subjected to high levels of repeated loading or injury, such as the loading that can occur when a person runs. This is particularly the case for articulating joints in the lower body that are subject to compressive forces, such as the joints located in the ankle, knee, hip, and spine.
In recent years, the resurfacing of cartilage surfaces has been widely studied in the orthopedic industry. One known method of resurfacing cartilage surfaces is referred to as “microfracture stimulation”. Instead of replacing damaged hyaline cartilage with an artificial cartilage implant, microfracture stimulation can be performed to stimulate the human body to replace the damaged cartilage with fibrous cartilage tissue (also referred to herein as “fibrocartilage”). Fibrocartilage is generally not as robust as hyaline cartilage, and typically has a higher coefficient-of-friction compared with that of hyaline cartilage. Nonetheless, such fibrocartilage provides many people with reduced pain, enabling them to assume more active lifestyles.
A conventional microfracture pick for use in performing microfracture stimulation has a handle, a shaft coupled to the handle, and a sharp, optionally angled tip disposed at a distal end of the shaft. For example, conventional microfracture picks can have tips that are optionally bent at angles of about 20°, 40°, 60°, or 90° relative to the longitudinal axis of the shaft. In a typical mode of operation, microfracture stimulation first involves the removal of the damaged layer of cartilage. The thickness of the damaged cartilage layer can typically vary from about 1 mm to 6 mm. The sharp tip of the microfracture pick is then driven about 2 mm to 5 mm through underlying subchondral bone in the region of the removed layer of cartilage to reach a blood supply. The microfracture pick is then removed, causing a small channel to remain in the subchondral bone. The microfracture pick is typically used to create a series of such channels through the subchondral bone. As a result, blood eventually travels along the series of channels and clots in the region of the removed cartilage layer, ultimately causing the formation of fibrocartilage.
When a surgeon uses such a conventional microfracture pick to perforate the subchondral bone of a patient, he or she may experience difficulties manually advancing the sharp tip through a hard cortical layer of the bone. This can be problematic since not advancing the microfracture pick deep enough into the bone may prohibit the formation of fibrocartilage in the region of the removed cartilage layer. To aid in advancing the sharp tip of the microfracture pick through the subchondral bone, surgeons have traditionally used a hammer or mallet to strike an end of the handle of the microfracture pick, while applying a downward pressure to the handle. However, such use of a hammer or mallet has drawbacks in that it can produce a shear force at the tip of the microfracture pick, potentially causing the tip to become broken or otherwise damaged. Such a broken tip can become a loose body in the surgical site, and can cause a delay in the progress of the microfracture procedure. In addition, the tip can skive across the bone surface, potentially causing the microfracture pick to impinge on and possibly damage surrounding tissue surfaces.
To address this problem, a strike plate can be directly attached to the shaft or handle of the conventional microfracture pick. Such a strike plate is typically attached to the shaft or handle perpendicular to the direction of the sharp tip of the microfracture pick. When a surgeon strikes the strike plate with a hammer or mallet, the resulting force causes the tip of the microfracture pick to advance through the subchondral bone. Directly attaching a strike plate to the shaft or handle of a microfracture pick also has drawbacks, however, in that it can make the microfracture pick heavy and cumbersome. The act of striking the strike plate so close to the patient's body can also be problematic, especially when performed near delicate joint access locations such as the ankle. The strike plate can also interfere with the microfracture procedure by preventing complete access to the surgical site, potentially making it extremely difficult for the surgeon to treat the entire affected surface area of the bone.
It would therefore be desirable to have a microfracture pick that avoids at least some of the drawbacks of the conventional microfracture picks discussed above.